Load compensating brake mechanism



April 20, 1954 T, H. BIRCH EI'AL LOAD COMPENSATING BRAKE MECHANISMOriginal Filed 'Aug. 23, 1948 2 Sheets-Sheet l TORS.

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April 20, 1954 T. H. BIRCH ETA]. 3

LOAD COMPENSATING BBAKE I MECHANISM Original Filed Aug. 23, 1948, I I 2Sheets-Sheet 2 Patented Apr. 20, 1954 LOAD C OMPENSATING BRAKE MECHANISMThomas H. Birch, Milwaukee, Wis., and Alfred Vincent Nystrom, Chicago,111.; said Nystrom assignor to said Birch Original application August23, 1948, Serial No.

45,755, new Patent No. 2,549,957, dated April 24, 1951. Divided and thisapplication November 21, 1949, Serial No. 128,668

1 Claim.

Our invention relates to mechanism whereby the brake cylinder levers ofrailroad cars are made more effective and involves air actuated meanshaving valved connection with the air supply or brake air line of thecar and controlled by the car load; said means being adapted to controlthe relation or distance between the connecting link pivots and thepivots at the outer ends or power arms of the levers in keeping with thecar load.

Our invention contemplates means whereby the power arms of the livelever and of the fulcrurn or floating lever are made more effective byshifting the pivotal connection of said levers with the connectin linkand thereby efiectively increasing the distance between the fulcrumpoints and the pivot points at the outer or power arms of both levers atthe same ratio during brake application of a loaded car, thus providinga load compensating arrangement whereby the force transmitted to the toprods of the brake rigging is increased in keeping with the increasedload of the car.

The objects and advantages of our invention will be readily comprehendedfrom the detailed description of the accompanying drawings, therein-Figure 1 is a perspective view, as viewed from beneath a railroad car,looking upwardly rearwardly of a portion of a car underframe, showing anair cylinder and connected levers and connecting link, with our improvedair actuated connecting link control.

Figure 2 is a perspective view of a portion of a freight car truck withportions of the brake rigging and body bolster broken away anddisclosing the valved air connection between the source of air supplyand our improved compensating mechanism.

The exemplification disclosed in Figure 1 consists of subject matterdivided from our application Serial Number 45,755 filed August 23, 1948,patented April 24, 1951, as 2,549,957 and shows the improved mechanismapplied to the brake rigging of a railroad freight car of which aportion of the underframing is disclosed.

The brake riggin involves the usual air cylinder ID with an air supplypipe I I and the piston push rod I 2 shown provided with a yoke portionI3 to which link or rod I4 is pivotally connected and which leads to theusual truck lever of the brake mechanism. The yoke like portion I3provides pivotal mounting for the power arm of live lever I5 whoseopposite end has a truck lever controlling rod pivotally connectedthereto; a portion of the rod being shown at I5. The lever I5intermediate its ends is provided with an elongated slot I'I disposedlengthwise of the lever which passes through and is supported by theusual lever guide it.

The closed end or head of cylinder I9 is provided with an apertured yokeor bracket I9 and receives the outer end of the power arm of the fulcrumor floating lever 20; the plurality of apertures or holes in the bracketI9 receive the pivot pin and permit angular adjustment of the floatinglever. Lever 29 is supported by guide 2|.

The lever 20', similar to live lever I5, is provided intermediate itsends with an elongated and lengthwisely disposed slot 22 and the twolever I5 and 29 are connected by the connecting rod 23 whose pivot pinspass loosely through the lever slots I1 and 22.

A suitable depending plate or bracket 22 is rigidly secured to the carunder-frame and is provided with a small air cylinder 25, having aspring controlled piston whose push rod is shown at 26. Disposed aboutor straddling the bracket, cylinder and push rod is a V-shaped yoke 21,whose ends are swiveled on or secured to the connecting rod 23. TheV-shaped yoke 21 and the cylinder push rod 26 are disposed away from theair cylinder ID and the push rod 26 is connected at 29 to the apexportion of the V-shaped yoke 27.

The push rod 26 is normally retracted into the cylinder, causing theV-shaped yoke to move therewith, thereby forcing and holding theconnecting rod. 23 and it pivot pins toward the upper ends of the slotsI7 and 22 (as viewed in Figure in both levers I5 and 29. This is thenormal or light car load position of the mechanism, at

which time no air is supplied to the cylinder 25.

Air is admitted to cylinder 25 when the car load reaches a prearrangedamount sufiicient to depress or lower the truck bolster, at which timeair will be admitted to cylinder 25 by pipe 29 during brake application.

Pipe 29 leads to a point adjacent the truck bolster, as shown in Figure2, where the bolster 30 has a control or three-way valve SI securedthereto and pipe 29 is connected with this valve 3!, which in turn hasconnection with the train line or air pipe 32.

The control valve 3i is shown in the nature of a suitable plunger type,with its plunger 33 depending vertically into proximity with a bracket34 shown secured on thespring plank 35 beneath the bolster 39. Undernormal or light car conditions, valve 3| will not admit air to pipe 29during brake applications.

Asthe car load on the bolster 30 increases and depresses the bolster,the valve plunger 33 will engage and be actuated by the bracket 34 andallow air from train or air line 32 to flow through the valve 3| andinto pipe 29 to cylinder 25 during brake applications. That is to say,as air from the train or air pipe 32 is admitted to conduit or pipe 29and thence into the closed end of the small cylinder 25, its piston pushrod 26 will be moved outwardly and cause the yoke 21 to pull connectingrod 23 toward the lower or right hand and of both slots l1 and 22 andthereby lengthen the power arms of both levers i5 and 2t! andconsequently increase the power of said levers for more eflicientbraking force and brake application.

As long as air is admitted to cylinder 25 the connecting rod 23 and itsfulcrum providing ends, for levers i5 and 20, will remain removed fromthe upper ends (as they appear in Figure 1) of the slots 11 and 22 andthereby increase the effective force of levers l5 and 2% of the loadedcar during brake applications on the train.

With a train of loaded cars, the brake force obtained with the usualbrake rigging decreases with the number of cars or increased train loadand as a result the stopping distance of the train far exceeds thatwhich would be obtained if the cars were empty. Our improved mechanismis designed to overcome this serious difficulty and to provide safertrain operation by automatically providing approximately the same brakeforce on loaded cars that exists during brake application with emptycars.

What we claim is:

In combination with the truck bolster of a railroad car having an airline, an air brake cylinder and its piston push rod, a live lever, afloating lever, both levers being actuated by said piston push rod, arigid connecting rod having pin and slot connection at its ends withsaid levers, and an auxiliary air cylinder with a cylinder push rod anda valve-controlled connection with the air line, operable by downwardmove-- ment of the truck bolster, a load compensating brake mechanismcomposed of a single-piece V-shaped yoke disposed. about and straddlingthe auxiliary. cylinder, with the ends of the oke arms, socketed attheir ends for passage of the connecting rod therethrough, while theapes: of the yoke has the auxiliary cylinder push rod pivotallyconnected thereto and the position of the yoke and connecting rodthereby controlled when air is admitted to the auxiliary cylinder duringbrake application.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 538,851 Teal May 7, 1895 521,553 Gilman et a1 Mar. 21, 084,313Sauvage Oct. 8, 1901 2,353,539 Farmer l- Nov. 28, 1944,

FOREIGN PATENTS Number Country Date 727,388 France June 17, 1932

